A Step-Iris Resonator for LSA Operation (Correspondence)

A step-iris resonator circuit which substantially increases the efficiency of limited-space-charge-accumulation (LSA) oscillators has been designed. The circuit design employs harmonic tuning that provides the proper impedances at the second and third harmonics of the oscillator frequency. The efficiency obtained with the step-iris resonator is about 1.7 times greater than that obtained with a conventional rectangular resonant iris.